When flooring material, particularly vinyl flooring material, is laid on a floor, the adjoining edges of the two pieces of flooring material must fit together precisely so that there are no gaps between the adjoining strips and no overlapping portions. To do this knives have previously been used to cut through overlapping and adjoining pieces of flooring material, so that the same cut was used to make the cut in both the upper and the lower pieces of flooring material. The result was usually a seam in which the edges were not perpendicular, and did not fit together very well.
Another method of cutting seams involved the use of an underscriber device, which hooked on the bottom edge of the material being cut, with a needle above this edge for gouging the top of the material. A cut was then made with a knife on the scribed line. The result was a rough and often irregular cut. The underscriber could not be used for all flooring materials.
To solve the difficulties of using a knife, with or without an underscriber, a dual cutting system was developed in which a first cutter, called a salvage edge cutter, cut the upper layer of flooring material using the edge of the upper layer of flooring material as a guide. This cut was made a few millimeters away from the edge. The salvage edge cutter consisted primarily of a guiding edge and a blade separated from the guiding edge by a few millimeters. As the guiding edge moved along the edge of the upper layer of flooring material it tended to average out the roughness of that edge, so that the cut made by the blade was relatively smooth.
A trace edge cutter was then used to follow the resulting edge and cut down into the lower layer of flooring material. The trace edge cutter was similar to the salvage edge cutter except the blade was closely adjacent to the guiding edge so that the blade essentially followed the edge of the flooring material.
These devices tended to be two to four centimeters wide. One used a single screw to hold the blade, and had a fixed guiding edge. Another used a single screw and pressure plate to hold the blade, with a moveable guide clamped by several screws. Another device used two screws to hold a moveable guide, one of which also held the blade.
Another device, called the Kombi, could be used as both a trace edge cutter and a salvage edge cutter. In this device, a fixed guiding edge was spaced from the blade by a spacer plate. The spacer plate was moveable from a position in which it left a gap between the blade and guiding edge, and a position in which it extended as far downward as the guiding edge so that the side of the spacing plate next to the blade became the guiding edge. The guiding edge itself remained fixed.
These prior art devices had all of the following disadvantages. They were narrow, and therefore unstable. As a result, it was difficult to hold the blades upright. The resulting seam was likely to be peaked or leave open spaces. In addition, as the guiding edge wore at its ends with use, the cutter would rock about the guiding edge, causing the blade to wander away from the edge of the material and create an open seam.
In addition, they used numerous screws, or if only one screw, the screw only adjusted the blade. If the guiding edge was adjustable, it was only adjustable below the base of the cutter, so that the base itself could never be a guiding edge. The guiding edge was narrow and could not function as a stable support.
In addition, the bases of these cutters were planar, and made of aluminum or BAKELITE, (a trade mark of Union Carbide Corp.) which would become scratched by grit moving under the bases, and would mark the floor. Aluminum also tended to peel, and be gouged by grit, and the pieces of aluminum that would be gouged out of the base would also tend to mark and gouge the floor.
Furthermore, the blades of these devices were susceptible to movement, and were not easily adjusted. If placed in a groove within the cutter, the blade tended to be damaged by contact with the edges of the groove.
These devices also only used one guide for trace edge cutting which tended to wear that guide excessively. In addition, these devices had thin length-wise handles, which were difficult and tiring to grip, and their guiding edges were not replaceable.
All of these disadvantages are solved by one or other of the embodiments of the present invention, and the present invention gives other advantages as set out in detail in this patent.